Abstract: The invention relates to a monitoring system (10, 20) for monitoring of at least a fixed but displaceable object in a volume, which object is provided with at least a marking means (13, 13a-13d, 23) in form of a light generating or reflecting device, which system at least comprises an optical recording unit (11, 21) for recording of an image of at least a part of the volume comprising said object provided with the marking means (13, 13a-13d, 23), device for transformation of said image to a digital representation of the same image, means (14) for comparison of the digital representation to a stored data-set, and device for generating a signal at the presence of a deviation at comparison of the digital representation to the stored data-set.

Abstract: The measuring apparatus serves for measuring the distance of an object from a measurement surface. The apparatus contains an illumination unit, which is preferably a laser. Furthermore the apparatus contains an optical image reproduction system with which a light ray projected onto the object by the illumination unit is imaged, after reflection, on an optical sensor. A two-dimensional charge-coupled semiconductor sensor should be used as optical sensor, which sensor has a plurality of electrodes arranged in the form of a matrix. To evaluate the position of a light spot-point of concentration on the image region of the charge-coupled semiconductor sensor all pulse trains should be evaluated which can be retrieved from illuminated electrode series. In this way a high resolution is achieved despite a relatively small number of electrodes in any one series.

Abstract: The invention relates to a device for determining the real or the virtual distance of a source of light from a measuring plane. Such devices are preferably employed in position detectors in which light produced by a light source is caused to impinge on the surface of the object to be measured, said light being reflected from said surface towards a photodetector. The light emitted by the light source is imaged at different points on said detector, this depending on the position of the surface of the object to be measured, it thus being possible to draw a conclusion as regards the position of said object. According to the invention, the imaging system and the position-sensitive detector form a rotationally symmetrical arrangement.

Abstract: A device for accurately measuring a dimension associated with a remote object without contacting the object itself is disclosed. A beam of light is directed at a surface of the object and a reflected portion of the beam is detected at a photodetector element. The particular dimension of the object is determined mathematically by measuring the distance by which the reflected light signal is offset from a predetermined point on the photodetector which is aligned with a reference plane at the object. By the use of two heads and respective light beams and photodetectors, a remote object's thickness can also be measured.In order to compensate for the angular relationship between the object's surface and that of the photodetector, a linearizing calibration circuit is included in which preset corrections are recorded in programmable memory units. The calibration settings are determined during manufacture and correct for each normally non-linear reading at incremental distances within a prescribed measurement range.